If your taxes owed (line 11) is really $6,930, then you should get the full $4K in child tax credits as best I can tell with those numbers. I'm not sure why Turbotax has something different. It sounds like Turbotax doesn't think your tax liability is $6,930, so it may only be giving you the $1,400 per kid.
Turbotax doesn't want to show you the whole return unless you pay them (that's how the tax prep programs normally work), so you probably can't look at the return. But it may have something where it will tell you what your child tax credit is and explain why it is what they calculated it to be. Poke around.